MathDB
isosceles wanted, tangent and secant from exterior point of a circle

Source: Switzerland - Swiss MO 2004 p1

July 19, 2020
geometryisoscelestangentsecant

Problem Statement

Let Γ\Gamma be a circle and PP a point outside of Γ\Gamma . A tangent from PP to the circle intersects it in AA. Another line through PP intersects Γ\Gamma at the points BB and CC. The bisector of APB\angle APB intersects ABAB at DD and ACAC at EE. Prove that the triangle ADEADE is isosceles.